An image forming apparatus such as a scanning apparatus or a printing apparatus is usually equipped with a mechanism for changing a conveying path of a paper. For example, if the image forming apparatus needs to perform a duplex scanning operation or a duplex printing operation on the paper, the paper should be moved to different conveying paths. Hereinafter, some conventional image forming apparatuses and associated methods for changing the conveying path of the paper will be illustrated in more details.
First of all, a first conventional image forming apparatus 1 will be illustrated with reference to FIG. 1. FIG. 1 is a schematic cross-sectional side view illustrating a first conventional image forming apparatus. As shown in FIG. 1, the image forming apparatus 1 comprises at least one paper 11, an input tray 12, a pick-up roller 13, a feed roller assembly 14, an optical photoconductive drum 15, a fusing roller assembly 17, a first conveying roller assembly 18, a movable stopping block 19, a second conveying roller assembly 20, a third conveying roller assembly 21, a fourth conveying roller assembly 22, a scanning unit 23, a reflective mirror 24, and an ejecting roller 25.
A process of conveying the paper 11 by the image forming apparatus 1 will be illustrated in more details as follows. Firstly, the paper 11 on the input tray 12 is transported by the pick-up roller 13, and thus the paper 11 is moved in the direction toward the feed roller assembly 14. Then, by the feed roller assembly 14, the paper 11 is controlled to be moved across the optical photoconductive drum 15. Consequently, an image formed on the optical photoconductive drum 15 is transferred onto a first surface of the paper 11.
As the paper 11 is continuously moved and transported across the fusing roller assembly 17, the image which is transferred to the first surface of the paper 11 can be firmly adsorbed onto the paper 11. Then, the paper 11 is transported by the first conveying roller assembly 18, and thus the paper 11 is moved in the direction toward the movable stopping block 19.
For performing a duplex printing task, the movable stopping block 19 is switched to the position which is indicated as solid lines (see FIG. 1). Under this circumstance, since the paper 11 is stopped by the movable stopping block 19, the paper 11 is allowed to be moved in the direction toward the second conveying roller assembly 20 (i.e. along the path A). Then, the paper 11 is transported by the second conveying roller assembly 20, and thus the paper 11 is moved in the direction away from the first conveying roller assembly 18.
When a tail edge of the paper 11 is moved across a protruding corner 261 of a supporting plate 26 along the path A, the rotating direction of the second conveying roller assembly 20 is changed. Consequently, the paper 11 is moved along the path C, and sequentially moved across the third conveying roller assembly 21, the fourth conveying roller assembly 22 and the feed roller assembly 14. Then, by the feed roller assembly 14, the paper 11 is controlled to be moved across the optical photoconductive drum 15 again. Consequently, an image formed on the optical photoconductive drum 15 is transferred onto a second surface of the paper 11.
Meanwhile, the movable stopping block 19 is switched to the position which is indicated as dotted lines (see FIG. 1). Consequently, the paper 11 is sequentially moved through the fusing roller assembly 17 and the first conveying roller assembly 18. Under this circumstance, since the paper 11 is stopped by the movable stopping block 19, the paper 11 is allowed to be moved in the direction toward the ejecting roller 25 (i.e. along the path B). Afterwards, the paper 11 is outputted to an outlet tray 27 of the image forming apparatus 1. At this moment, the task of conveying the paper 11 by the image forming apparatus 1 is completed.
Hereinafter, a second conventional image forming apparatus 3 will be illustrated with reference to FIGS. 2 and 3. FIG. 2 is a schematic cross-sectional side view illustrating a second conventional image forming apparatus. FIG. 3 is another schematic cross-sectional side view illustrating the second conventional image forming apparatus of FIG. 2. As shown in FIGS. 2 and 3, the image forming apparatus 3 comprises a pick-up arm 31, a first conveying roller assembly 32, a second conveying roller assembly 33, a third conveying roller 34, a fourth conveying roller 35, a fifth conveying roller 36, and a movable stopping block 37.
A process of conveying a paper 30 by the image forming apparatus 3 will be illustrated in more details as follows. Firstly, the paper 30 is transported by the pick-up arm 31, and thus the paper 30 is moved in the direction toward the first conveying roller assembly 32 along a path B′. Then, by the first conveying roller assembly 32, the paper 30 is transported to a region between the third conveying roller 34 and the fourth conveying roller 35. Before the paper 30 is contacted with the third conveying roller 34 and the fourth conveying roller 35, the paper 30 is moved across a scan region D. Consequently, a scanning operation is performed on a first surface of the paper 30.
During the scanning operation is performed on the first surface of the paper 30, the movable stopping block 37 is located at the position as shown in FIG. 2. Consequently, the paper 30 is clamped and transported by the third conveying roller 34 and the fourth conveying roller 35, and the paper 30 is moved in the direction toward the second conveying roller assembly 33.
After the paper 30 is moved for a specified distance in the direction away from the third conveying roller 34 by the second conveying roller assembly 33, the movable stopping block 37 is switched to the position as shown in FIG. 3. In addition, the rotating direction of the second conveying roller assembly 33 is changed. Consequently, the paper 30 is moved along the path C′, transported through a region between the fourth conveying roller 35 and the fifth conveying roller 36, and moved in the direction toward the first conveying roller assembly 32. The paper 30 is moved across the scan region D again, and thus a scanning operation is performed on a second surface of the paper 30.
However, the image forming apparatus 1 and the image forming apparatus 3 still have some drawbacks. For example, it is necessary to additionally install the movable stopping block 19 or 37 in the image forming apparatus 1 or 3 in order to switch the conveying path of the paper. Since the movable stopping block 19 or 37 requires a large layout space, the overall volume of the image forming apparatus 1 or 3 will be increased. Moreover, if the moving paper collides with the movable stopping block 19 or 37, the possibility of damaging or bending the paper will be increased.
Therefore, there is a need of providing a device and a method for changing a conveying path of the paper in order to overcome the above drawbacks.